TABLE II -2 



MID -RANGE NAVIGATION SYSTEMS 



Estimated Estimated 

 System Useful Range Accuracy 



Frequency 

 Range 



Comments 



Decca 



Two- 



Range 



EPI 



175nm 



250] 



25-200 ft 110-170 kc 



50-200 ft 



1.85 mc 



Lorac 



135 nm 



25-100 ft 



1.7 to 2 .5mc 



Raydist 

 DM 



25-200nm 25-250 ft 



Circular geometry survey 

 system . Night effect re - 

 duces range to 40 miles or 

 less. Continuous tracking. 



Circular geometry survey 

 system used by USC and GS . 

 Requires operators at 2 

 shore stations . Single-user 

 system . Night effect re - 

 duces range . 



Hyperbolic geometry port- 

 able survey system; re- 

 quires 3 shore stations; 

 used widely for offshore 

 seismic work. Continuous - 

 tracking, multi-user cap- 

 ability . Night effect reduces 

 range . 



1 . 6 to 5 . mc Circular geometry survey 

 system; requires 2 shore 

 sites . Lx3w-power buoy 

 equipment available . Con- 

 tinuous-tracking, multi-user 

 capability . Night effect re - 

 duces range . 



artbur ai.Hittlc.idtr. 



